The invention relates to a device for acquiring information contained in a phosphor layer.
X-rays are taken, especially for medical purposes, by using phosphor layers and having the radiation passing through an object, i.e. a patient, saved as a latent image in the phosphor layer. In order to read out the latent image, the phosphor layer is radiated with excitation light thereby emitting an emission light corresponding to the latent image, which is received by an optical detector and converted into electric signals. If necessary, the electric signals can be further processed and displayed on a monitor or read out by a suitable output device such as a printer for example.
The German Patent No. DE 198 59 747 C1 describes a similar device in which some reflection layers are provided between the phosphor layer and detector. If necessary, an absorption filter for the absorption of the excitation light may also be provided. In this way the excitation light is prevented from reaching the detector, which could adulterate the acquisition of the emission light coming from the phosphor layer. Furthermore, the light source can be fitted with a reflection layer for the reflection of light portions which are not designed or suitable for the excitation of the emission light. In this way such light portions are prevented from impinging on the phosphor layer or other components of the device and from reaching the detector through reflection and/or diffusion, which could also adulterate the acquisition of the emission light.
In general this device facilitates the acquisition of the emission light with high reliability. However, in certain applications, the degree of reliability necessary for that particular application may not always be ensured, for example when using certain types of detectors and/or sources of light and/or certain kinds of phosphor layers.